Salvador Portillo-Saravia, a member of the MS-13 street gang, was charged with raping an 8-year-old girl at her Fairfax County home last month. But he never should have been in Fairfax in the first place.

Federal officials deported Portillo-Saravia, of Sterling, to El Salvador in 2003, and he sneaked back in illegally. Now, officials are wondering why a much-touted federal program didn't catch him before the rape.

Loudoun authorities ran Portillo-Saravia's fingerprints through a federal database, but despite the 2003 deportation, nothing was found. He was released after 12 hours behind bars.

Portillo-Saravia, 29, is now the subject of a manhunt by local police and federal marshals.

Officials involved with Secure Communities and immigration experts said the incident points to confusion about how the program should work and to gaps in the immigration database. Many people who were deported before 2005, including Portillo-Saravia, are not in the fingerprint database, ICE officials said.

Jail officials in Virginia and Maryland who have relied on the program said they were not aware of the gap in the database.

"I was under the impression that everybody they had contact with was in the system," Henrico County Sheriff Michael L. Wade said.

"Secure Communities is a very good program, but it's not a magic solution and shouldn't be sold that way," said Jessica Vaughan, a senior policy analyst at the Center for Immigration Studies, a Washington think tank that advocates tighter immigration controls. "This is why you do go after low-level offenders, because it can turn out they are a threat to public safety."

Secure Communities was rolled out in October 2008 amid much fanfare as a way to transform immigration enforcement, ICE officials said then. Jails would fingerprint all arrestees, not just those suspected of being in the country illegally. Those prints would run through FBI and Department of Homeland Security databases, and ICE would flag immigration offenders for possible deportation.

But it didn't work in Portillo-Saravia's case.

Loudoun jail deputies submitted Portillo-Saravia's fingerprints on Nov. 21 and received a "no match" message. Brian P. Hale, a spokesman for ICE, said Loudoun then should have done a manual record check or contacted ICE if the person was "foreign-born and of concern to local law enforcement."